Song meaning in short: It’s a sexual song (obviously) and the whole “chest pains, love must be opened” thing basically means 1. She wants him to open his heart (not literally, of course), 2. Chest pains is what happens when she holds her sexual urges out, and 3. Splash out/opening your chest also literally means splashing out her breasts (in a sexual way).

That’s the very short meaning, If you want a longer, more detailed one, let me know. :)